The present invention relates to a method and apparatus for detecting a particle present on a thin film board, a semiconductor board or a photomask in the process of fabricating a semiconductor chip or a liquid crystal product. The present invention also relates to a method and apparatus for detecting a defect produced at a circuit pattern and inspecting the situation which may have caused production of a particle or a defect in a step of fabricating a device which is subjected to a measurement by analyzing the detected particle or defect.
In a step of fabricating a semiconductor device, when a particle is present on a semiconductor board (wafer), the particle may constitute the cause of an insulation failure or a shortcircuit of the wiring. Further, in accordance with the demand for miniaturization of a semiconductor element, a fine particle also constitutes a cause of an insulation failure of a capacitor or the destruction of a gate oxide film. The particles are mixed at various stages due to various causes, and they may be produced from a movable portion of a carrying apparatus, produced from the human body, produced by a reactor in a processing apparatus by a process gas, or mixed with a drug or a material.
Similarly, also in a step of fabricating a liquid crystal display element, when a particle is mixed on a pattern or some defect is produced, the display element cannot be used. The situation stays the same also in a step of fabricating a printed board, and a shortcircuit of a pattern or a failure in a connection may be caused by such a particle.
As one of the technique for detecting a particle on a semiconductor board, JP-A-62-89336 (Patent publication 1), discloses a method of effecting a highly sensitive and highly reliable inspection of a product for a particle or other defect by eliminating false information in a pattern by irradiating a laser beam onto a semiconductor board, detecting light scattered from a particle produced when the particle is adhered onto the semiconductor board, and comparing a result of inspecting a semiconductor board of the same kind that was inspected immediately therebefore. Further, JP-A-63-135848 (Patent publication 2) discloses a method which involves irradiating laser light onto a semiconductor board, detecting light scattered from a particle which is adhered on the semiconductor board and analyzing the detected particle by laser photoluminescence or an analyzing technology of secondary X-ray analysis (XMR).
Further, as a technique for inspecting a wafer to detect the presence of a particle, there is a method which involves irradiating coherent light to the wafer, removing light emitted from a repeated pattern on the wafer using a spatial filter and emphasizing the received pattern to detect a particle or a defect which is not provided with repeatability. Further, a particle inspecting apparatus is described in JP-A-1-117024 (Patent publication 3) in which a circuit pattern formed on a wafer is irradiated from a direction which is inclined relative to a main group of linear lines of the circuit pattern by 45 degrees to prevent 0-order diffracted light from the main group of linear lines from being incident on an aperture of an object lens. According to this technique, it is also proposed to block light from other groups of linear lines, which are not the main group of linear lines using a spatial filter.
Further, an apparatus and a method of inspecting an object for a defect in the form of a particle or the like is described in, for example, JP-A-8-271437 and JP-A-2000-105203 (Patent publications 4). Particularly, in JP-A-2000-105203, it is proposed to change the size of a detected pixel by switching the detecting optical system. Further, a technique for measuring the size of a particle is described in, for example, JP-A-2001-60607 (Patent publication 5).
However, according to the techniques proposed in the above-cited publications, consideration is not given to a constitution capable of detecting a fine particle or a defect, on a board on which a repeated pattern are mixed, and a non repeated pattern with high sensitivity and at high speed. That is, according to the technologies disclosed in the above-described publications, consideration is not given to a constitution capable of achieving a detection sensitivity (minimum detected particle dimension) equivalent to that of a repeated pattern even at areas other than the repeated pattern portion of, for example, a memory cell portion.
Further, according to the technologies disclosed in the above-described publications, consideration is not given to a constitution capable of promoting a good sensitivity in detecting a small particle or a defect at the 0.1 μm level in a region having a high pattern density. Further, according to the technologies disclosed in the above-described publications, consideration is not given to a constitution capable of promoting a good sensitivity in detecting a particle or a defect that produces a shortcircuiting of wirings or a good sensitivity in detecting a particle in the shape of a thin film. Further, according to the technology disclosed in JP-A-2001-60607, consideration is not given to a constitution capable of promoting an increased accuracy in the measurement of a particle or a defect.
Further, according to the technology disclosed in JP-A-2001-60607, consideration is not given to a constitution capable of promoting a good sensitivity in detecting a particle on a surface of a wafer formed with a transparent thin film.